Knotless suture anchor

ABSTRACT

A suture anchor comprises a tubular body having an axial bore therethrough and having one or more purchase enhancements on an exterior surface of the body adapted to enhance purchase of the body within a bone hole, such as threads. A lateral port passes through the body from the bore to the exterior surface and is formed of a slot entering the body from its proximal end. A length of suture for attaching soft tissue to bone passes down along the exterior surface over the one or more purchase enhancements, over a distal end of the body, up into the bore through and then back out of the bore and up along the exterior surface over the one or more purchase enhancements.

BACKGROUND

This application relates to suture anchors and more particularly toknotless suture anchors.

Suture anchors are commonly employed to attach soft tissue such astendons or ligaments to bone. For instance, in a rotator cuff repairsuture is passed through a detached or damaged portion of a rotator cufftendon. A suture anchor is implanted into the adjacent bone. Byattaching the suture to the anchor the tendon is pulled into contactwith the bone to promote adhesion of the tendon to the bone.

Such procedures are often performed arthroscopically through a narrowcannula. This reduces trauma to the patient but makes attachment of thesuture to the anchor using a knot more difficult. Knotless sutureanchors may be employed which allow a surgeon to tension the suture to adesired degree and then affix to suture to the anchor without having totie a knot. A typical knotless anchor is shown in US Patent PublicationNo. 20080033460 wherein the suture is trapped between an inner memberand outer member of an anchor in coaxial relation to one another. Whilesuch anchors work well their complexity increases manufacturing cost andmakes it difficult to form the anchor of bioabsorbable materials whichoften are more frangible and less strong than metals or traditionalpolymers.

SUMMARY OF THE INVENTION

A suture anchor according to the present invention comprises a tubularbody having an axial bore therethrough and having a proximal end and adistal end. One or more purchase enhancements on an exterior surface ofthe body are adapted to enhance purchase of the body within a bone hole.A lateral port passes through the body from the bore to the exteriorsurface, the port comprising a slot into the body from the proximal end.

Preferably, the slot has a first portion extending from the proximal endof the body and a second portion extending partially circumferentiallyabout the body. In one aspect of the invention the second portion alsoextends proximally. The second portion preferably extendscounterclockwise about the body when viewed from the body proximal end.Preferably, the second portion passes through the body at an obliqueangle to a distally extending portion of a central longitudinal axisthrough the body, whereby to allow suture to pass in a distal directionthrough the port and into the axial bore while forming an oblique anglewith itself.

In one aspect of the invention, the slot further comprises a sutureengaging lip to restrain proximal movement of suture out of the slot.

Preferably, the purchase enhancements comprise at least one thread aboutthe body. More preferably, they further comprise one or more additionalthread leads at a proximal portion of the body.

Preferably, the suture anchor is provided sterile and packaged within asterile bacteria-proof enclosure. In one aspect of the invention, thebody is formed of a biodegradable material.

A method according to the present invention provides for attachingtissue to bone. It comprises the steps of: threading a length of suturethrough the tissue; loading the length of tissue into a suture anchorwhich comprises a tubular body having an axial bore therethrough andhaving a proximal end and a distal end, one or more purchaseenhancements on an exterior surface of the body adapted to enhancepurchase of the body within a bone hole, and a lateral port through thebody from the bore to the exterior surface, the port comprising a slotinto the body from the proximal end, the step of loading comprisingpassing the length of suture through the axial bore from its distal endand out of the body through the slot; implanting the suture anchor intothe bone with the suture passing from the tissue, between the bone andthe exterior surface of the body into the axial bore distal end, out ofthe axial bore through the slot and between the bone and the bodyexterior surface proximal of where the length of suture passes out ofthe slot.

Preferably, the slot comprises a suture engaging lip and the methodfurther comprises retaining the length of suture in the slot with thelip prior to implanting the suture anchor into the bone.

In one aspect of the invention, the suture is loaded into the sutureanchor manually without further assistance of a suture passing device.

Preferably, the purchase enhancements comprise exterior threads and thestep of implanting the suture anchor into the bone comprises threadingthe suture anchor into the bone hole. More preferably, the exteriorthreads comprise one or more additional thread leads at a portion of theanchor proximal to where the suture exits the axial bore through theslot and the method comprises implanting this portion within corticalbone.

In one aspect of the invention, the step of implanting the suture anchorinto the bone comprises engaging the suture between the suture anchorand the bone at the bone hole and then threading the suture anchor intothe bone hole while maintaining an essentially fixed length of thesuture between the bone hole and the tissue. This maintains a constanttension on the tissue during implantation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front plan view of a suture anchor according to the presentinvention;

FIG. 2 is a cross-sectional view of the suture anchor of FIG. 1implanted into a bone;

FIG. 3 is a graph of failure modes with respect to the location andangle of a suture passing port of the suture anchor of FIG. 1;

FIG. 4 is a graph of fixation strength with respect to the location andangle of a suture passing port of the suture anchor of FIG. 1;

FIG. 5 is a graph of fixation strength versus bone quality for severalthreading options of the suture anchor of FIG. 1;

FIGS. 6 A to C are side sectional views of the suture anchor of FIG. 1and a driver therefor;

FIG. 7 is a cross-section taken along lines 7-7 of FIG. 6A;

FIG. 8 is a perspective view of an alternate driver head according tothe present invention;

FIG. 9 is a wire drawing in perspective of the driver head of FIG. 8received within a further embodiment of a suture anchor according to thepresent invention;

FIG. 10 is a close-up perspective view of the driver and suture anchorof FIG. 9;

FIG. 11 is a perspective view of the driver and suture anchor of FIG. 9;

FIG. 12 is a front plan view of a further embodiment of a suture anchoraccording to the present invention;

FIG. 13 is a sectional view taken along lines 13-13 of FIG. 11;

FIG. 14 is an end view of a further embodiment of a suture retainingclutch according to the present invention;

FIG. 15 is an end view of a further embodiment of a suture retainingclutch according to the present invention;

FIG. 16A is a front elevation view of a further embodiment of a sutureretaining clutch according to the present invention;

FIG. 16B is an end view from a distal end of the suture retaining clutchof FIG. 16A;

FIGS. 17 A and B are sectional views of a further embodiment of a sutureretaining clutch according to the present invention;

FIG. 18A is a perspective view of a suture driver handle embodying afurther embodiment of a suture retaining clutch according to the presentinvention;

FIG. 18B is an end view from a proximal end of the suture driver handleof FIG. 18A;

FIG. 19 is a side elevation view of a suture threader according to thepresent invention;

FIG. 20 is a side elevation view of an alternate usage of the suturethreader of FIG. 19;

FIG. 21 is a side elevation view of a further embodiment of a suturethreader according to the present invention;

FIG. 22 A to D illustrate a further embodiment of a suture threaderaccording to the present invention;

FIG. 23A is a top plan view of a further embodiment of a suture threaderaccording to the present invention showing the braided tube in partialcut-awy; and

FIG. 23B is an end view of the suture threader of FIG. 23A.

DETAILED DESCRIPTION

FIG. 1 depicts a knotless suture anchor 10 according to the presentinvention. It comprises a body 12 having a distal end 14 and proximalend 16. The proximal end 16 has a hexagonal-shaped tool receiving recess18. It will be understood to one of skill in the art that alternativetool engagements may be employed. A slight inward taper 19 is providedat the distal end 14 to ease insertion of the anchor 10 into a bone hole(not shown in FIG. 1) and provides an initial fixation of the suture(not shown in FIG. 1) prior to threading the anchor into the hole.

The body 12 has a distal threaded portion 20 and a proximal threadedportion 22. A single exterior thread 24 threads about the body 12 toform the distal threaded section 20. This thread 24 extends nearly tothe distal end 14, ending about 0.1 to 0.3 inches short thereof foreasier insertion into a bone hole (not shown in FIG. 1). However, one ormore additional thread leads 26 begin towards the proximal end 16 toform a multi-fluted threading which distinguishes the proximal threadedportion 22. Each individual thread start 24 and 26 have the same pitchas the thread 24 in the distal threaded section 20, the presence of theone or more additional thread leads 26 provides the proximal threadedportion 22 with an increased effective thread pitch. However, the pitchof each thread lead in the proximal threaded portion 22 remains the sameas the pitch of the thread 24 to eliminate axial compression effectsfrom the threads as the anchor 10 is threaded into a bone hole.Preferably, there are four thread leads in the proximal threaded portion22, the thread 24 and three additional thread leads 26. The majordiameter of the proximal threaded portion 22 is preferably somewhatlarger than that of the distal threaded portion 20. Rather than havethreads with a sharp outer edge the threads 24 and 26 preferably have arounded our blunted profile to minimize stress on suture that iscompressed against them. While the anchor body 12 is shown with threads24 and 26, especially for smaller diameters, the threads could bereplaced with annular flanges or other purchase enhancements appropriatefor a push-in anchor versus a threaded anchor. Even with the threads 24and 26, smaller diameters of the anchor body 12 may be appropriate topush in rather than thread in.

A lateral port 28 passes through the body 12 at an oblique angle to adistally extending longitudinal axis 30 of the body 12 and is disposedwithin the proximal threaded portion 22. It provides for passage ofsuture (not shown in FIG. 1) between an inner axial cannulation 32through the body 12 and an exterior 35 of the body 12. Such functionwill be explained in detail below.

The body 12 is formed of a suitable biocompatible material and ispreferably provided sterile and packaged within a bacteria-proofenclosure (not shown) such that it is ready for a sterile surgicalprocedure. Many biodegradable materials have less strength and are morebrittle than non-biodegradable materials such as PEEK or stainlesssteel. The simple design of the body 12, without complicated moving orinteracting parts, allows easier use of such biodegradable materialswhile maintaining the structural integrity of the anchor 10.

The novel suture anchors of the present invention may be made from ametallic material, a non-biodegradable polymer, a biodegradable polymer,or a composite of a biodegradable polymer or copolymer and a bioceramic.The term biodegradable as used herein is defined to mean materials thatdegrade in the body and then are either absorbed into or excreted fromthe body. The term bioceramic as defined herein is defined to meanceramic and glass materials that are compatible with body tissue. Thebioceramics are preferably biodegradable.

The metallic materials that can be used to manufacture the anchors ofthe present invention include stainless steel, titanium, alloys ofnickel and titanium, or other biocompatible metallic materials.

The non-biodegradable materials that can be used to manufacture theanchors of the present invention include polyethylene, polypropylene,PEEK, or other biocompatible non-absorbable polymers.

The biodegradable polymers that can be used to manufacture the anchorsused in the present invention include biodegradable polymers selectedfrom the group consisting of aliphatic polyesters, polyorthoesters,polyanhydrides, polycarbonates, polyurethanes, polyamides andpolyalkylene oxides. Preferably, the biodegradable polymers arealiphatic polyester polymers and copolymers, and blends thereof. Thealiphatic polyesters are typically synthesized in a ring openingpolymerization. Suitable monomers include but are not limited to lacticacid, lactide (including L-, D-, meso and D,L mixtures), glycolic acid,glycolide, .epsilon.-caprolactone, p-dioxanone (1,4-dioxan-2-one),trimethylene carbonate (1,3-dioxan-2-one), .delta.-valerolactone, andcombinations thereof.

The bioceramics that can be used in the composite anchors of the presentinvention include ceramics comprising mono-, di-, tri-, .alpha.-tri-,.beta.-tri-, and tetra-calcium phosphate, hydroxyapatite, calciumsulfates, calcium oxides, calcium carbonates, magnesium calciumphosphates. It is particularly preferred to use a .beta.-tritricalciumphosphate. In addition to bioceramics, bioglasses may also be used inthe composite screws. The bioglasses may include phosphate glasses andbioglasses.

Suitable biocompatible synthetic polymers can include polymers selectedfrom the group consisting of aliphatic polyesters, poly(amino acids),copoly(ether-esters), polyalkylene oxalates, polyamides, tyrosinederived polycarbonates, poly(iminocarbonates), polyorthoesters,polyoxaesters, polyamidoesters, polyoxaesters containing amine groups,poly(anhydrides), polyphosphazenes, polyurethanes, poly(etherurethanes), poly(ester urethanes), poly(propylene fumarate),poly(hydroxyalkanoate) and blends thereof.

For the purpose of this invention aliphatic polyesters include, but arenot limited to, homopolymers and copolymers of lactide (which includeslactic acid, D-,L- and meso lactide); glycolide (including glycolicacid); .epsilon.-caprolactone; p-dioxanone (1,4-dioxan-2-one);trimethylene carbonate (1,3-dioxan-2-one); alkyl derivatives oftrimethylene carbonate; .delta.-valerolactone; .beta.-butyrolactone;.gamma.-butyrolactone; .epsilon.-decalactone; hydroxybutyrate;hydroxyvalerate; 1,4-dioxepan-2-one (including its dimer1,5,8,12-tetraoxacyclotetradecane-7,14-dione); 1,5-dioxepan-2-one;6,6-dimethyl-1,4-dioxan-2-one; 2,5-diketomorpholine; pivalolactone;.alpha., .alpha. diethylpropiolactone; ethylene carbonate; ethyleneoxalate; 3-methyl-1,4-dioxane-2,5-dione;3,3-diethyl-1,4-dioxan-2,5-dione-; 6,6-dimethyl-dioxepan-2-one;6,8-dioxabicycloctane-7-one and polymer blends thereof. Additionalexemplary polymer or polymer blends include, by non-limiting example, apolydioxanone, a polyhydroxybutyrate-co-hydroxy-yvalerate,polyorthocarbonate, a polyaminocarbonate, and a polytrimethylenecarbonate. Aliphatic polyesters used in the present invention can behomopolymers or copolymers (random, block, segmented, tapered blocks,graft, triblock, etc.) having a linear, branched or star structure.Poly(iminocarbonates), for the purpose of this invention, are understoodto include those polymers as described by Kemnitzer and Kohn, in theHandbook of Biodegradable Polymers, edited by Domb, et. al., HardwoodAcademic Press, pp. 251-272 (1997). Copoly(ether-esters), for thepurpose of this invention, are understood to include thosecopolyester-ethers as described in the Journal of Biomaterials Research,Vol. 22, pages 993-1009, 1988 by Cohn and Younes, and in PolymerPreprints (ACS Division of Polymer Chemistry), Vol. 30(1), page 498,1989 by Cohn (e.g., PEO/PLA). Polyalkylene oxalates, for the purpose ofthis invention, include those described in U.S. Pat. Nos. 4,208,511;4,141,087; 4,130,639; 4,140,678; 4,105,034; and 4,205,399.Polyphosphazenes, co-, ter- and higher order mixed monomer basedpolymers made from L-lactide, D,L-lactide, lactic acid, glycolide,glycolic acid, para-dioxanone, trimethylene carbonate and E-caprolactonesuch as are described by Allcock in The Encyclopedia of Polymer Science,Vol. 13, pages 31-41, Wiley Intersciences, John Wiley & Sons, 1988 andby Vandorpe, et al in the Handbook of Biodegradable Polymers, edited byDomb, et al., Hardwood Academic Press, pp. 161-182 (1997).Polyanhydrides include those derived from diacids of the formHOOC—C.sub.6H.sub.4-O—(—CH.sub.2).sub.m-O—C.sub.6H.sub.4-COOH, where “m”is an integer in the range of from 2 to 8, and copolymers thereof withaliphatic alpha-omega diacids of up to 12 carbons. Polyoxaesters,polyoxaamides and polyoxaesters containing amines and/or amido groupsare described in one or more of the following U.S. Pat. Nos. 5,464,929;5,595,751; 5,597,579; 5,607,687; 5,618,552; 5,620,698; 5,645,850;5,648,088; 5,698,213; 5,700,583; and 5,859,150. Polyorthoesters such asthose described by Heller in Handbook of Biodegradable Polymers, editedby Domb, et al., Hardwood Academic Press, pp. 99-118 (1997).

Turning also to FIG. 2, the suture anchor 10 is shown disposed within abone hole 34 with a length of suture 36 passing through the anchor body12 and also through a tendon (such as a tendon in a rotator cuff) 38. Aloop 40 of the suture 36 passes through the tendon 38 and its free ends42 then pass down along a first side 44 of the anchor body 12, beingtrapped between the anchor body 12, especially by the threads 24 and 26,and bone 46 forming the bone hole 32. The free ends 42 then pass overthe distal end 14, into the axial cannulation 32 and then back out ofthe cannulation 32 through the lateral port 28. From here they passbetween a second side 48 of the anchor body 12, being trapped betweenthe body 12 and the bone 46. Other threading arrangements are possible.For instance, rather than passing the loop 40 through the tendon 38 asecond anchor, or row of anchors, (not shown) can be placed beneath thetendon 38 with the suture 36 passing from these anchor(s) up through thetendon 38 and to the anchor body 12 or to multiple anchor bodies 12.

Turning also to FIGS. 3 and 4, the location of the lateral port 28affects the strength of the fixation of the anchor body 12 to the bone46 and also the affixation of the suture 36 to the bone 46 and body 12.A more distal location of the port 28 provides higher fixation strengthbut the failure mode then tends to be evulsion of the anchor body 12from the bone hole 34. A failure mode which involves slipping of thesuture 36 rather than evulsion of the anchor body 12 is preferred so asto not leave a foreign body free within a patient's joint in an event offailure. Also, an evulsion failure could lead to damage of the bone 46.The angle at which the port 28 passes through the body 12 with respectto the longitudinal axis 30 affects fixation strength with a moreoblique angle enhancing fixation.

Additionally, the size and direction which the port 28 passes throughthe body can affect the functionality and fixation strength of thedesign. The cross sectional area of the port 28 is provided withsufficient dimension to pass a desired size and quantity of suture(s)through the port 28. The port 28 should not be so small as to damage thesuture(s) while transiting the port 28 during loading, deployment or inuse. Similarly, passing a disproportionate quantity of suture through anundersized port 28 may result in damage to the anchor body 12 itself.Conversely, the port 28 should not be so large as to minimize thebenefit to fixation strength which is derived from the meandering courseof suture 36 through the system. An excessively large port size mayresult in an undesirable degradation of the structural strength of theanchor body. The size of the port may be optimized to provide ease ofuse and avert damage to the system, while providing benefit within thecontext of additional fixation strength.

It is favorable to choose the direction of the port 28 as it passesthrough the body at such angles and locations which promote passage ofsuture 36 through the system. Obtuse angles formed by the suture 36during loading and use are most desirable, as they minimize contactfriction at corners and subsequently, reduce loading forces and wear andincrease robustness of the entire system. The direction of the port 28may be optimally provided in a compound, oblique direction and offsetlocation with respect to the longitudinal axis. The compound obliquedirection and offset location provide an exit of the port 28 whichcoarsely approximates the tangent of the helices of the thread starts ina distal-to-proximal direction.

This direction and location has been shown to positively affect fixationstrength. As the anchor is threaded into a bone hole, it is theorizedthat the compound oblique direction and offset location of the port 28promotes a gentle fold of the suture 36 as it exits the port 28, causingthe suture 36 to fall easily within the roots between the proximalthread starts. In this context, a port 28 oriented radially normal tothe longitudinal axis, for example, would require a sharp fold of thesuture 36 as it exits the port 28. The sharp fold thusly presents asharp transition as the anchor descends into the bone hole past the port28, thereby weakening the bone by shearing along the wall of the bonehole, ultimately reducing fixation. By not creating sharp bends in thesuture 36 it is possible to provide an anchor having smaller dimensionswithout adding too much additional stress to the suture 36.

Other forms of providing a gentle transition may include the use of a“break edge”, fillet or chamfer in the vicinity of the port 28. However,in designs incorporating minimum wall thickness of the anchor, largetransition features may result in undesirable increases in the crosssectional area of the port 28.

Turning also to FIG. 5, one can see that the number of thread leads 26in the proximal threaded section 22 affects suture 36 fixation betweenthe bone 46 and the anchor body 12. More thread leads enhance suchsuture 36 fixation. The top line shows optimal fixation with four leads,the thread 24 and three additional thread leads 26.

Ideally, anchor body 12 fixation and suture 36 fixation are optimized toprovide maximum anchor body 12 fixation while still providing suture 36slip as the predominate failure mode over anchor body 12 evulsion.

Turning also now to FIGS. 6A, 6B and 6C, the suture anchor body 12 isshown loaded onto an anchor driver 50. The driver comprises an elongatedcannula 52 having a driving handle 54 at a proximal portion 56 thereofand a driver tip 58 at a distal portion 59 thereof. The driver tip 58engages the tool recess 18 on the anchor body 12. Preferably the drivertip 58 is keyed to the anchor body tool recess 18 in such a fashion thatthe anchor body 12 is placed onto the driver 50 in only one rotationalorientation such that a surgeon can determine such orientation by therotational position of the handle 54. (See FIG. 7 in which a spline 60on the driver tip 58 fits into a spline receiving cut-out 62 on theanchor boy 12.

A suture passer 64, such as the CHIA PERCPASSER (available from DePuyMitek, Inc., Raynham, Mass.), an elongated braided Nitinol wire 66 witha distal suture grasping loop or kite 68, is engaged to the driver 50and anchor body 12. It passes into a central lumen 70 of the cannula 52from a proximal slot 72, out of the lumen 70 from a distal slot 74, overa removable ramp 76 and into the anchor body cannulation 32 through thelateral port 28, with the suture loop 68 extending out of the distal end14 of the body 12. The wire 66 is flexible but retains some rigidity andthe ramp 76 provides a smooth entry angle into the lateral port 28. Atensioning clutch 78 is interposed between the handle 54 and the cannula52. A proximal portion 80 of the wire 66 passes through a suturemanagement passage 82 through the clutch 78. During a procedure, afterthe suture 36 has been passed through the tendon 38, the free ends 42are pulled out of the procedure cannula (not shown) to a point outsideof the patient's body and loaded through the suture loop 68.

After the free ends 42 are loaded into the suture passer 64 it is drawnup the cannula 52 leaving the free ends 42 to pass up through the anchorbody cannulation 32 from its distal end 14, out through the lateral port28, over the ramp 76, into the lumen 70 through the distal slot 72, outof the lumen 70 through the proximal slot 72 and through the clutchsuture management passage 82 as depicted in FIG. 6B. The ramp 76 nolonger being needed is removed as shown in FIG. 6C. Preferably, the ramp76 fits to the cannula 52 via a snap-fit to provide easy removal. Theanchor is now ready for implantation.

To complete the procedure the suture 36 is tensioned through the suturetension clutch 78 to a desired tension. The anchor body 12 is thenthreaded into the pre-drilled bone hole 34 via the driver 50. The clutch78 plays out the free ends 42 as the body 12 approaches and enters thehole 34 to maintain proper tension on the suture 36 and allows thesuture 36 to move into the bone hole 34 from the clutch 78 rather thanfrom the tissue and thus avoids spooling of the suture 36 onto theanchor body 12 as it is threaded into the hole 34. The anchor bodypreferably completes only a partial turn, such as one quarter turn fromthe time the suture 36 is pinched by the port 28 entering the hole 34and the anchor body 12 is fully seated therein. The anchor body 12,especially in its interior, and the suture 36 can be formed of materialsor have their surfaces enhanced with materials or procedures which lowerfriction and enhance slipping of the suture 36 as the anchor isdeployed. When fully deployed the proximal end 22 of the anchor body 12is preferably below the bone 46 within the bone hole 34. The driver 50is removed and the free ends 42 trimmed leaving the anchor 10 in placeas shown in FIG. 2.

FIG. 8 illustrates an alternative embodiment of an insertion tool 100and FIG. 9 illustrates an alternative embodiment of an anchor 102according to the present invention, each of these being adapted for usetogether. The anchor 102 has a structure similar to the anchor 10 withthe exception of an axial boss 104 within its axial cannulation 106which mates with a distal axial slot 108 in a distal driving portion 110of the insertion tool 100. Also, the axial cannulation is enlargedradially where the driving portion 110 is received such that an interiorcannulation 112 of the driving portion 110 has the same interiordiameter as a distal portion 114 the anchor axial cannulation 106 andthe boss 104 extends radially into the slot 108 to a depth matching theinterior diameter of the interior cannulation 112, providing a smoothtransition within the of the interior cannulation 112 and axialcannulation 106 eliminating discontinuities upon which suture can snagduring rotational deployment of the anchor 102. The boss 104 providesadditional engagement between the insertion tool 100 and the anchor 102.

Turning also to FIGS. 10 and 11, the boss 104 aligns circumferentiallywith a lateral port 116 on the anchor. A suture ramp 118 aligns on theinsertion tool 100 with the port 116. The alignment of the boss 104 withrespect to the port 116 and the slot 108 with respect to the ramp 118puts the port 116 and ramp 118 into circumferential alignment with oneanother.

The ramp 118 is formed of a molded polymer having an arcuate suturereceiving groove 120 which extends radially outwardly to guide sutureand/or a suture grasper 122 out of a slot 124 on the insertion tool 100and into the port 116 without sharp transitions and with the suture orsuture grasper 122 forming an oblique angle with respect to itself as itenters the port 116. The ramp 118 also bears a pair of C-shaped snapclips 126 which snap onto and off of the insertion tool 100 for easyremoval of the ramp 118 during the procedure previously described. Agrasping tab 128 provides a gripping surface for easy manual removal ofthe ramp 118 and also provides a surface upon which to placeinstructions for use.

As shown in FIG. 11 a T-shaped handle 130 on the suture grasper 122preferably has finger lands 132 for easy manipulation of the suturegrasper 122. A suture clutch 134 which normally holds the suture andthen releases it as torque is provided to a handle 136 on the insertiontool 100 is shown distal of the handle 136 but could be incorporatedtherein. Details on preferred clutch mechanisms are provided laterherein.

FIG. 12 illustrates a further embodiment of a suture anchor 140according to the present invention. It is similar to the prior sutureanchors 10 and 102; however, instead of a port it carries an axial slot142 at its proximal end. The slot 142 terminates at its distal end 144with a return portion 146 which extends proximally and circumferentiallyalong a path of a thread start 147 providing an overall hook shape tothe slot 142. Being open at its proximal end allows for easier threadingof a suture grasper (not shown in FIG. 12).

Ease of threading is so improved that the grasper can be omitted inwhich case during the procedure a surgeon can directly thread a suture148 through a main axial cannulation 150 of the anchor 140, feeding itinto the slot 142 and seating it within the slot return portion 146. Aprocedure with the anchor 140 would proceed as previously described withthe surgeon pre-drilling a hole in a bone and passing suture 148 throughtissue, preferably in an arthroscopic procedure through a cannula (thecannula, tissue and bone not being shown in FIG. 12). With free ends ofthe suture 148 outside of the patient's body the surgeon passes themthrough the cannulation 150 and seats the suture within the returnportion 146. The anchor 140 would then be loaded onto an insertion toolsuch as the tool 100 or 50 and installed into the bone as previouslydescribed, the return portion 146 holding the suture similarly to theaforementioned ports. Preferably the return portion passes into thecannulation 150 at an oblique angle as described with respect to theprior ports thus allowing the suture 148 to pass into the cannulation150 through the return portion 146 while keeping an oblique angle withrespect to itself.

The clutch 134 comprises a disk shaped body 152 having a distal portion154 which attaches to an elongated cannula 156 which itself terminatesin the hexagonal driving portion 110. A proximal portion 158 of the body152 attaches to the insertion tool handle 136 outwardly radially ofwhere the cannula 156 attaches to the body 152. An axial slot 160, asbest seen in FIG. 13, leads into the body 152 and receives and grabs thesuture 148. Preferably its interior surface 162 is formed of a rubber orother resilient material to enhance the grip with the suture 148. Torqueapplied to the handle 136 is transmitted through the clutch body 152 tothe cannula 156. The body 152 is formed of a material, such as a hardrubber, having sufficient resilience to allow the slot 160 to open underthe influence of such torque and relax the grip on the suture 148. Thus,the clutch 134 normally grips the suture to maintain tension but relaxesthat grip as the handle 136 is torqued during implantation of the anchor140 allowing suture 148 to slide through the clutch 134.

FIG. 14 illustrates an alternate embodiment of a clutch body 164according to the present invention. It comprises a pair of somewhatradial slots 166 which spiral inwardly radially in a direction in whichtorque would be applied to an associated handle (not shown in FIG. 14).

FIG. 15 illustrates a further embodiment of a clutch body 170 comprisinga plurality of radially extending arms 172, each having circumferentialsuture receiving slots 174 therein. A cannula attachment location 176 islocated in the center of the body 170 and handle attachment locations178 are located on the arms outwardly radially of the slots 174.

FIGS. 16 A and B illustrate a further embodiment of a clutch mechanism180 which comprises a rigid outer handle gripping portion 182 and aradially interior resilient insert 184. A proximal end 186 of the insert184 attaches to the outer handle 182 and a distal end 188 of the insert184 attaches to a cannula 190. Suture 192 feeds into a gap 194 betweenthe outer handle 182 and the insert 184 through a radial slot 196 in thehandle 182. The gap 194 is sized to grip the suture 192. Application oftorque to the outer handle 182 twists the insert 184 thereby opening thegap 194 and allowing slippage of the suture 192 therethrough.

FIGS. 17 A and B illustrate a further embodiment of a clutch mechanism200 comprising a pair of radial flanges 202 extending outwardly radiallyfrom a cannula proximal portion 204. A resilient material 206 such asrubber affixes to both sides of the flanges 202. An outer handle 208comprises two halves 210, each of which attach to one of the flanges 202and which are spaced apart from the opposing flange 202 to create suturereceiving slots 212. The slots 212 can have flared openings 214 with asuture retaining lip 216 therein. Suture 218 is gripped within the slots212 by compression between the outer handle 208 and the resilientmaterial 206 on the flange 202 as shown in FIG. 17 A. Application oftorque to the outer handle 208 compresses the resilient material betweenthe handle 208 and flanges 202 to open the slots 212 to release thesuture as shown in FIG. 17 B.

FIGS. 18 A and B illustrate an additional embodiment of a clutchmechanism 220. A handle 222 comprise an outer cylindrical grippingportion 224 and a central axial core 226, the gripping portion 224 beingattached to the core 226 via a plurality of radial ribs 228. One pair ofribs 230 extend slightly off axis and adjacent to each other and thegripping portion 224 is open between them forming a radially extendingaxial slot 232 in the handle 222. Near a proximal end 234 of the handle222 a retainer member 236 sits within the slot 232 extending from one ofthe ribs 230 toward the adjacent rib 230. It has a flared opening 238and a retaining lip 240 to ease entry of suture 242 into the slot 232with the lip 240 holding it from falling out. A resilient material 244in the slot 232 grips the suture 242. Torque applied to the grippingportion 224 tends to open the slot 232 releasing the tension on thesuture 242.

Threading the suture 148 through the cannulation 150 of the sutureanchor 140 of FIG. 12 can be accomplished manually without assistancefrom a threading device. However, a simple converging threader 300 asillustrated in FIG. 19 can further simplify the procedure. The threader300 comprises an open braided tube 302 having one end 304 insertedthrough the cannulation 150 and a second expanded end 306 into which oneor more sutures 148 can be pushed by hand. The threader 300 ispreferably woven from a flexible biocompatible material and provided incombination with the anchor 140, with the threader 300 received throughthe cannulation 150, and with both the threader 300 and anchor beingsterile and packaged within a sterile bacteria-proof package (notshown). When a surgeon is ready to load sutures 148 into the anchor 140the combination of the anchor 140 and threader 300 are removed from thesterile package and the sutures 148 are pushed into the threaderexpanded end 306. Tension is applied to the other end 304 causing theexpanded end 306 to close and travel through the cannulation 150carrying the sutures 148 therethrough. The procedure can then becompleted as aforementioned.

Alternatively, as shown in FIG. 20, the sutures 148 can be merelystitched through the braided tube 302. If the weave is open enough theycan be stitched by hand or they can be stitched with needles (notshown). The tube 302 is then drawn through the cannulation 150 as inFIG. 19.

As shown in FIG. 21, a threader 310 can be formed from a tube 312 whichis not necessarily braided but rather provided with axial slits 314 atone end 316 to form a mouth 318 for receiving the suture 148. Grippingenhancements such as teeth 320 can be provided within the mouth 318 tohelp retain the suture 148 therein as the threader 310 passes throughthe cannulation 150.

To ensure good closure of the expanded end 306 of the threader 300 ofFIG. 19 it can be modified with additional closures as shown in FIGS. 22A through D. For instance a simple spring metal snap element 322 can beprovided to a braided tube 324, the element 322 having a first openposition as shown in FIG. 22B and a second relaxed closed position asshown in FIG. 22C. After insertion of the sutures 148 with the element322 in the open position is squeezed to pop it into the closed position.A loading suture loop 324 can be employed about the element 322 toprovide the squeezing force for closure and also to further compress thesutures 148 within the tube 324. A separate loading suture loop 324 canalso be provided alone and woven through the braid of the tube 324 insubstitution of the element 322.

Alternatively, the braiding of the tube 324 can be woven to encourageclosure, especially if the material is resilient, and to hold theexpanded end 316 open a stretcher 326 can be inserted therein as shownin FIGS. 23 A and B. In its simplest form the stretcher 326 comprises atube 328 having a full length side opening 330 whereby after the suture148 is loaded into the expanded end 316 the tube 328 is removedtherefrom with the suture 148 passing through the opening 330 to allowremoval of the tube 328.

The invention has been described with reference to the preferredembodiments. Obviously, modifications and alterations will occur toothers upon reading and understanding the preceding detaileddescription. It is intended that the invention be construed as includingall such modifications and alterations insofar as they come within thescope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A method for attaching tissue to bone comprisingthe steps of: threading a length of suture through the tissue; loadingthe length of suture into a suture anchor which comprises a tubular bodyhaving an axial bore therethrough and having a proximal end and a distalend, one or more purchase enhancements on an exterior surface of thebody adapted to enhance purchase of the body within a bone hole, and alateral port through the body from the bore to the exterior surface, theport comprising a slot into the body from the proximal end, the step ofloading comprising passing the length of suture through the axial borefrom its distal end and out of the body through the slot; implanting thesuture anchor into the bone with the suture passing from the tissue,between the bone and the exterior surface of the body into the axialbore distal end, out of the axial bore through the slot and between thebone and the body exterior surface proximal of where the length ofsuture passes out of the slot; and wherein the purchase enhancementscomprise exterior threads and wherein the step of implanting the sutureanchor into the bone comprises threading the suture anchor into the bonehole.
 2. The method according to claim 1 wherein the slot comprises asuture engaging lip and the method further comprises retaining thelength of suture in the slot with the lip prior to implanting the sutureanchor into the bone.
 3. The method according to claim 1 wherein thesuture is loaded into the suture anchor manually without furtherassistance of a suture passing device.
 4. The method according to claim1 wherein the exterior threads comprise one or more additional threadleads at a portion of the anchor proximal to where the suture exits theaxial bore through the slot and wherein the method comprises implantingthis portion within cortical bone.
 5. A method according to claim 1wherein the step of implanting the suture anchor into the bone comprisesengaging the suture between the suture anchor and the bone at the bonehole and then threading the suture anchor into the bone hole whilemaintaining an essentially fixed length of the suture between the bonehole and the tissue.